Powdered medicine is administered into a body cavity such as the nasal cavity or the oral cavity, and air ways such as the trachea, a bronchus or a lung by means of spraying or inhalation. For example, powdered medicine is administered into the nasal cavity or the air ways of a patient suffering from nasal allergy or asthma. Recently, attention has been given to a drug delivery system in which medicine is absorbed into the bloodstream through the mucous membrane of the nasal cavity or lung and it is attempted to administer powdered medicine via the mucous membrane.
When medicine is administered in the above manner, a powdered medicine administering device is used. Powdered medicine administering devices are classified into two types according to the storage system for the powdered medicine.
In the first type of powdered medicine administering device, a quantity of powdered medicine to be administered in a single operation is accommodated in an appropriate container. A unit-dose powdered medicine is accommodated in an appropriate capsule. Therefore, a unit-dose of powdered medicine is administered at each administering operation. In the second type of powdered medicine administering device, a quantity of powdered medicine to be administered in a plurality of operations is accommodated in an appropriate container. Each time an administering operation is carried out, an accurate unit-dose of powdered medicine is extracted from the container in which the powdered medicine is accommodated. In the present invention, a quantity of powdered medicine to be administered in a single operation is defined as a unit-dose, and a quantity of powdered medicine to be administered in a plurality of operations is defined as a multi-dose. However, in some cases, an administering operation in which powdered medicine, accommodated in the form of a unit-dose, is administered for each unit-dose is referred to as a unit-dose, and an administering operation in which powdered medicine accommodated in the form of a multi-dose is administered for each unit-dose is referred to as a multi-dose.
As an example of the unit-dose powdered medicine administering device by which powdered medicine is sprayed into the nasal cavity, a powdered medicine administering device has been proposed by the present inventors (disclosed in Japanese Patent Publication No. 63-6024). Concerning the unit-dose inhaler by which powdered medicine is inhaled into the air ways, a large number of devices have been proposed. For example, there is provided an inhaler in which capsules made of nonpoisonous material such as gelatin are used. In each capsule, a predetermined quantity of unit-dose powdered medicine is accommodated. In this type of inhaler, a capsule opening device is provided, by which a hole is formed in a capsule inserted into the inhaler, that is, a capsule opening device is provided, by which a hole is formed by various means.
This accommodated powdered medicine is inhaled through a hole made in the capsule by the action of an air flow caused by the user. The empty capsule is taken out from the inhaler, and a new capsule is accommodated in the inhaler. In the inhaler of the prior art disclosed in the U.S. Pat. Nos. 3,906,950 and 4,013,075, when holes are made at both ends of a capsule, the capsule is held in a stationary condition while the powdered medicine is inhaled. The powdered medicine is taken out from the capsule by the action of an air flow passing through the capsule generated as a result of inhalation.
In the case of another type inhaler, as disclosed in the U.S. Pat. Nos. 3,807,400 and 3,991,761, a capsule is previously opened by an appropriate means, and then the capsule is moved by the action of an air flow generated by inhalation. Due to the foregoing action, the capsule is made completely empty.
In the case of still another type inhaler of the prior art disclosed in the European Patent Publication No. 0211595, a plurality of capsules are not used, but a disk-shaped pack is charged into the inhaler, and a series of bubbles are provided around the pack under the condition that the distances from the bubbles to center of the pack are the same. A predetermined quantity of powdered medicine is accommodated in these bubbles. This pack composes a portion of the inhaler and is put on a rotatable circular tray around the central axis. In this tray, holes are made at positions corresponding to each bubble, and when each bubble is moved and broken by an appropriate device, powdered medicine is taken out from the bubble and inhaled.
An example of the multi-dose powdered medicine administering device used for inhalation into the air ways is disclosed in the European Patent Publication No. 0069715. This multi-dose powdered medicine administering device includes a container accommodating a predetermined quantity of medicine, and a device for taking out powdered medicine accommodated in the container so as to prepare for the administration of the medicine. This administration preparation device is composed of a plate, the thickness of which is predetermined, and through-holes, the number of which is predetermined, are made in the plate. This plate is capable of moving from a position at which a portion of the through-holes are filled with powdered medicine taken out from the container by a mechanical means, to a position at which the holes filled with the medicine are located in the passage. When the user inhales through an inhalation port communicated with this passage, air enters the passage, so that powdered medicine can be taken out from the through-hole. There is provided a scraper, which scrapes powdered medicine on the container side in the through-hole made on the plate. According to the inventors who applied for the European Patent, the through-holes are completely filled with powdered medicine by the action of this scraper. Therefore, a constant dose can be ensured. According to this European Unexamined Patent Publication, it is described that the scraper is optionally provided. However, in order to appropriately operate the inhaler, it is necessary to provide the scraper. The reason is that the dose greatly differs when this scraper is not provided. The reason why is described as follows. Since the fluidity of the powdered medicine to be used is low, it frequently occurs that the individual through-holes are not completely filled with powdered medicine.
When a comparison is made between the unit-dose powdered medicine administering device and the multi-dose powdered medicine administering device, the multi-dose powdered medicine administering device tends to be preferably used from the viewpoint of convenience and marketability.
However, there is a serious problem to be solved in the conventional multi-dose powdered medicine administering device. As described above, according to the conventional multi-dose powdered medicine administering device, a quantity of powdered medicine necessary for one administering operation is continuously and quantitatively divided from a large quantity of collective powdered medicine and then the divided powdered medicine is administered. However, the above operation is very difficult in view of the physical property of powdered medicine such as a change in the density of collective powdered medicine and a tendency of collective powdered medicine.
In order to solve the above problems, several proposals have been made. For example, as disclosed in the aforementioned European Patent Publication No. 0069715 (Japanese Examined Patent Publication No. 1-47190), a through-hole, the capacity of which is predetermined, is continuously filled with powdered medicine pressed by a scraper. However, even when this method is adopted, the following problems may be encountered. For example, when the overall medicine administering device is vibrated, the bulk density of powdered medicine is changed, so that the actual quantity of powdered medicine filled into the through-hole is changed. As a result, the quantity of powdered medicine to be administered fluctuates.
In Japanese Unexamined Patent Publication No. 3-18376, a multi-dose medicine administering device is disclosed, in which a large quantity of powdered medicine is compressed, and the compressed body of powdered medicine is quantitatively divided into pieces. According to the above method, when powdered medicine is compressed, a quantity of divided medicine is ensured to be constant. However, even in this method, the following disadvantages may be encountered. By the influence of vibration given to the overall medicine administering device, the density of compressed powdered medicine is changed. As a result, the weight of the divided piece made of compressed powdered medicine is changed, so that a quantity of powdered medicine to be administered to a patient is changed.